Development of the imaging system to evaluate of blood flow distribution and metabolic activity in myocardial microcirculation.

我们构建了心肌代谢活动和血流分布成像的荧光显微镜系统。为了在活体条件下用活体视频显微镜测量微循环中的红细胞速度，开发了新的软件。在时间序列录像图像中沿毛细血管设置一条线段，然后沿该段构建时空图像。估计反映红细胞速度的时空图像中条纹的角度，以计算红细胞速度矢量图。我们已经成功地利用我们的视频显微镜系统和时空图像分析方法对体内微循环进行了定量评估。局部心肌对缺氧的易感性是不同的；然而，局部心肌缺氧的动力学以及局部心肌缺氧对血流异质性的依赖性还不是很清楚，特别是在微循环水平上。因此，我们评估了心肌表面NADH在氧合逐步变化过程中的荧光，并将NADH荧光与血流分布进行了比较，将NADH荧光分成0.1×0.1-到0.4×0.4-mm^2个区域，其大小类似于一个微循环单元，由单个毛细血管前小动脉灌流。在另一只显示稳定斑片状荧光图案的低氧灌流心脏中，注入氚标记的去甲基米帕明，并用数字摄影测量其沉积分布，即心外膜各层内的相对血流分布。NADH荧光强度高的区域倾向于接受低流量；区域流量-荧光相关性显著。这些结果表明，易受缺氧影响的地区也很难从缺氧中恢复过来，而地区对缺氧的脆弱性与微循环水平上的区域血流异质性高度相关。

We constructed the fluorescence microscope system for imaging of myocardial metabolic activity and blood flow distribution. To measure erythrocyte velocities in microcirculation under in-vivo condition with an intravital videomicroscope, the newly software was developed. A line segment was set along the capillaries in time-sequential videotaped images and then a spatiotemporal image was constructed along that segment. The angle of striped pattern in the spatiotemporal image which reflects the erythrocyte velocity, was estimated to compute erythrocyte velocity vector mapping. We have succeeded in quantitatively evaluating the in-vivo microcirculation with our videomicroscope system and by spatiotemporal image analyzing method. Regional myocardial vulnerability to dysoxia is heterogeneous ; however, the dynamics of regional dysoxia and the dependence of regional dysoxia on flow heterogeneity are not well understood, especially at a microcirculatory level. Thus, we evaluated epimyocardial NADH fluorescence during stepwise changes in oxygenation and made a comparison between NADH fluorescence and flow distributions, resolved into 0.1×0.1- to 0.4×0.4-mm^2 regions the sizes comparable to a microcirculatory unit, which perfused by a single precapillary arteriole. In another hypoxia-perfused hearts showing the stable patchy fluorescence pattern, tritium-labeled desmethylimipramine was infused and its deposition distribution, i.e., relative flow distribution within epimyocardial layers was measured by digital radiography. The region of higher NADH fluorescence tended to receive lower flow ; the regional flow-fluorescence correlation was significant. These results suggest that regions vulnerable to dysoxia are also hard to recover from dysoxia and that regional vulnerability to dysoxia is highly relevant to regional flow heterogeneity at a microcirculatory level.